German, Italian and Spanish foreign ministries announced today that Syrian ambassadors are being expelled - following similar moves by Britain, France, Australia and Canada after a massacre in which the United Nations says families were shot at close range in their homes.

The ambassador to Germany, Radwan Loutfi, was today given 72 hours to leave Germany.

Foreign Minister Guido Westerwelle said Germany and its allies hope "that this unambiguous message does not fall on deaf ears in Damascus".

The Italian Foreign Ministry said Ambassador Khaddour Hassan was called to the ministry and informed of his new status - which was also extended to an unspecified number of Syrian officials.

Spain said it was giving Syrian Ambassador Hussam Edin Aala and four other diplomats based in Madrid three days to leave the country.

The actions being taken increase pressure on Damascus after a massacre in which the United Nations says families were shot at close range in their homes.

The killings last Friday in Houla, a collection of farming villages in Syria's Homs province, were one of the deadliest single events in the 15-month-old uprising against President Bashar Assad's rule. The UN said 49 children and 34 women were among the 108 people killed.

French President Francois Hollande told reporters that Ambassador Lamia Shakkour will be notified "today or tomorrow" that she must leave.

Hollande said that after high-level discussions with David Cameron and UN Secretary General Ban Ki-moon, it had been decided to deploy "a certain number of ... pressure tactics" againstSyria, including the expulsion of the ambassador.

In Canada, Foreign Minister John Baird said in a statement that the Syrian diplomats and their families have five days to leave Canada. Another Syrian diplomat expected in Canada will be refused entry.

Baird said these "Syrian representatives are not welcome in our countries while their masters in Damascus continue to perpetrate their heinous and murderous acts".

In Canberra, Australian Foreign Minister Bob Carr said Charge d'Affaires Jawdat Ali, the most senior Syrian diplomat in Australia, is to be expelled along with another diplomat from the Syrian Embassy. He said they were told to leave the country within 72 hours, in response to the massacre in Houla.

"This is the most effective way we've got of sending a message of revulsion of what has happened in Syria," Carr said.

In a statement, he called the killings a "hideous and brutal crime" and said Australia would not engage with the Syrian government unless it abides by a UN cease-fire plan.

In Vienna, Foreign Ministry spokesman Nikolaus Lutterotti said the Syrian ambassador is being summoned to the ministry where officials will deliver a very hard protest about the massacre.

When asked if the expulsions were EU-wide, Lutterotti said this had not yet been decided. He said the ambassador to Austria would not be expelled as he holds an additional function as the representative to the UN organisations in Vienna.

The UN estimates 9,000 people have been killed since the uprising began in March 2011.

Hollande said today that Paris will host a meeting in early July of the so-called Friends of Syria seeking a diplomatic solution to the conflict.

Many Syrian opposition figures are based in France, Syria's former colonial ruler.